Lee celebrates his stunning hat-trick (Getty Images).

By Richard Gibson, PA Sport, Durban

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Australia broke their own record of one-day matches without defeat to ensure they enter the semi-final stage of the World Cup on the back of nine victories.

They have won 15 consecutive one-day internationals in all, a run which started on January 11 against England, beating their run of 14 games without defeat in 1999-2000, which incorporated a washout.

Adam Gilchrist powered them to victory over fellow semi-finalists Kenya with 112 deliveries unused and five wickets in hand in the day-nighter at Kingsmead.

The opener flayed the Kenyan attack in a chase of 175, making 67 off just 43 balls.

His contribution to the top of the innings, which included three sixes and nine fours, made sure that they extended their winning run - they beat the record of 11 consecutive ODI wins set by the West Indies when they secured a final-over success over England earlier in this tournament - ahead of Tuesday's last-four meeting with Sri Lanka in Port Elizabeth.

Gilchrist flung his forearms through anything erring in line or length and the ninth of his fours, a cut off leg-spinner Collins Obuya, brought up his half-century.

He followed that with two towering sixes over midwicket in the same over.

But a delivery angled across him from Peter Ongondo ended his 56-minute assault.

He lost opening partner Matthew Hayden in the sixth over, following a 50-run stand for the first wicket when the left-hander tucked Ongondo to square leg.

Australia's pursuit did experience mid-innings discomfort, supplied by 39-year-old left-arm spinner Aasif Karim, who claimed three wickets without conceding a run to claim the man-of-the-match award.

Ricky Ponting was trapped leg before, left-hander Darren Lehmann snicked to stand-in wicketkeeper David Obuya and Brad Hogg, promoted in the order, was well held low down by the bowler off a thick inside edge.

Karim's overall figures of 8.2-6-7-3 also earned him a standing ovation from a crowd enchanted by the Kenyan dream.

Having lost four wickets for 19 runs in six overs, however, as they slipped to 117 for five, the reigning champions were held together by Andrew Symonds and Ian Harvey, who both took their toll on the expensive Collins Obuya.

The sixth-wicket pair shared an unbroken 61-run stand to snuff out hopes of Kenya's biggest shock of all, carried out in the field without captain Steve Tikolo (throat infection), wicketkeeper Kennedy Obuya (bruised elbow) and Maurice Odumbe and Thomas Odoyo (both groin).

Tikolo's half-century bolstered Kenya after Brett Lee's hat-trick threatened to undermine them earlier in the day.

Paceman Lee became the fourth bowler in World Cup history to achieve the feat, following Sri Lankan Chaminda Vaas earlier in this tournament, Saqlain Mushtaq and Chetan Sharma.

But Tikolo shared two purposeful stands; Ravindu Shah helping to contribute 79 for the fourth wicket and Hitesh Modi adding 49 more for the fifth.

Those partnerships added respectability as Kenya, who face India in the second semi-final here in Durban on Thursday, scrambled to 174 for eight.

Lee provided an Australian side, lacking Michael Bevan due to a back twinge, with a destructive start to the Super Six match. He did the damage in his second over after Ricky Ponting won the toss.

Kennedy Obuya's departure was a painful one as a sharply-rising delivery struck him on the elbow and careered into the stumps.

A clutch of Australian fielders surrounded Obuya, writhing in agony on the floor, and he was eventually led from the field by two of his team-mates before heading to hospital for X-rays, which revealed no fracture.

The delay did not distract Lee's focus, however, as a ball of full length induced an uncertain poke from Brijal Patel for Ponting to take a smart catch to his left at second slip.

Then, with the crowd roaring Lee on, he produced a yorker which flicked the pad of David Obuya and dislodged the off-bail.

Australia were made to work for their victory, however, by the industry of Hitesh Modi, who compiled an unbeaten 39, and some late hitting by Martin Suji, including a six over extra cover off Andy Bichel.

Although this tournament of surprises failed to deliver its biggest yet, Kenya should not be underestimated by India at the same ground in the second semi-final on Thursday.